Question

Calculate the molecular masses of the following :
(a) Hydrogen, H₂
(b) Oxygen, O₂
(c) Chlorine, Cl₂
(d) Ammonia, NH₃
(e) Carbon dioxide, CO₂

(Atomic masses : H = 1 u ; O = 16 u ; Cl = 35.5 u ; N = 14 u ; C = 12 u)

Answer 1

(a) Given:
Atomic mass of H = 1 u
Therefore, molecular mass of H₂ can be calculated as follows:
1 × 2 = 2
Hence, molecular mass of H₂ is 2 u.

(b) Given:
Atomic mass of O = 16 u
Therefore, molecular mass of O₂ can be calculated as follows:
16 × 2 = 32
Hence, molecular mass of O₂ is 32 u.

(c) Given:
Atomic mass of Cl = 35.5 u
Therefore, molecular mass of Cl₂ can be calculated as follows:
35.5 × 2 = 71
Hence, molecular mass of Cl₂ is 71 u.

(d) Given:
Atomic mass of N = 14 u
Atomic mass of H = 1 u
Therefore, molecular mass of NH₃ can be calculated as follows:
(1 × 14) + (3 × 1) = 17
Hence, molecular mass of NH₃ is 17 u.

(e) Given:
Atomic mass of C = 12 u
Atomic mass of O = 16 u
Therefore, molecular mass of CO₂ can be calculated as follows:
(1 × 12) + (2 ×16) = 44
Hence, molecular mass of CO₂ is 44 u.